(function(name, factory) {
	if (typeof window === "object") {
		window[name] = factory();
	}
})("Ribbons", function() {
	var _w = window,
		_b = document.body,
		_d = document.documentElement;
	var random = function() {
		if (arguments.length === 1) {
			if (Array.isArray(arguments[0])) {
				var index = Math.round(random(0, arguments[0].length - 1));
				return arguments[0][index];
			}
			return random(0, arguments[0]);
		} else if (arguments.length === 2) {
			return Math.random() * (arguments[1] - arguments[0]) + arguments[0];
		}
		return 0;
	};
	var screenInfo = function(e) {
		var width = Math.max(0, _w.innerWidth || _d.clientWidth || _b.clientWidth || 0),
			height = Math.max(0, _w.innerHeight || _d.clientHeight || _b.clientHeight || 0),
			scrollx = Math.max(0, _w.pageXOffset || _d.scrollLeft || _b.scrollLeft || 0) - (_d.clientLeft || 0),
			scrolly = Math.max(0, _w.pageYOffset || _d.scrollTop || _b.scrollTop || 0) - (_d.clientTop || 0);
		return {
			width: width,
			height: height,
			ratio: width / height,
			centerx: width / 2,
			centery: height / 2,
			scrollx: scrollx,
			scrolly: scrolly
		};
	};
	var mouseInfo = function(e) {
		var screen = screenInfo(e),
			mousex = e ? Math.max(0, e.pageX || e.clientX || 0) : 0,
			mousey = e ? Math.max(0, e.pageY || e.clientY || 0) : 0;
		return {
			mousex: mousex,
			mousey: mousey,
			centerx: mousex - screen.width / 2,
			centery: mousey - screen.height / 2
		};
	};
	var Point = function(x, y) {
		this.x = 0;
		this.y = 0;
		this.set(x, y);
	};
	Point.prototype = {
		constructor: Point,
		set: function(x, y) {
			this.x = x || 0;
			this.y = y || 0;
		},
		copy: function(point) {
			this.x = point.x || 0;
			this.y = point.y || 0;
			return this;
		},
		multiply: function(x, y) {
			this.x *= x || 1;
			this.y *= y || 1;
			return this;
		},
		divide: function(x, y) {
			this.x /= x || 1;
			this.y /= y || 1;
			return this;
		},
		add: function(x, y) {
			this.x += x || 0;
			this.y += y || 0;
			return this;
		},
		subtract: function(x, y) {
			this.x -= x || 0;
			this.y -= y || 0;
			return this;
		},
		clampX: function(min, max) {
			this.x = Math.max(min, Math.min(this.x, max));
			return this;
		},
		clampY: function(min, max) {
			this.y = Math.max(min, Math.min(this.y, max));
			return this;
		},
		flipX: function() {
			this.x *= -1;
			return this;
		},
		flipY: function() {
			this.y *= -1;
			return this;
		}
	};
	var Factory = function(options) {
		this._canvas = null;
		this._context = null;
		this._sto = null;
		this._width = 0;
		this._height = 0;
		this._scroll = 0;
		this._ribbons = [];
		this._options = {
			colorSaturation: "80%",
			colorBrightness: "60%",
			colorAlpha: 0.65,
			colorCycleSpeed: 6,
			verticalPosition: "center",
			horizontalSpeed: 200,
			ribbonCount: 4,
			strokeSize: 0,
			parallaxAmount: -0.5,
			animateSections: true
		};
		this._onDraw = this._onDraw.bind(this);
		this._onResize = this._onResize.bind(this);
		this._onScroll = this._onScroll.bind(this);
		this.setOptions(options);
		this.init();
	};
	Factory.prototype = {
		constructor: Factory,
		setOptions: function(options) {
			if (typeof options === "object") {
				for (var key in options) {
					if (options.hasOwnProperty(key)) {
						this._options[key] = options[key];
					}
				}
			}
		},
		init: function() {
			try {
				this._canvas = document.createElement("canvas");
				this._canvas.style["display"] = "block";
				this._canvas.style["position"] = "fixed";
				this._canvas.style["margin"] = "0";
				this._canvas.style["padding"] = "0";
				this._canvas.style["border"] = "0";
				this._canvas.style["outline"] = "0";
				this._canvas.style["left"] = "0";
				this._canvas.style["top"] = "0";
				this._canvas.style["width"] = "100%";
				this._canvas.style["height"] = "100%";
				this._canvas.style["z-index"] = "-1";
				this._canvas.style["background-color"] = "rgba(224,219,219,0.17)";
				this._canvas.id = "bgCanvas";
				this._onResize();
				this._context = this._canvas.getContext("2d");
				this._context.clearRect(0, 0, this._width, this._height);
				this._context.globalAlpha = this._options.colorAlpha;
				// 这里可以设置是否随着窗口的滚动而滚动
				window.addEventListener("resize", this._onResize);
				window.addEventListener("scroll", this._onScroll);
				// 这里设置添加的位置
				var body_ = document.getElementsByTagName('body')[0];
				body_.appendChild(this._canvas);
			} catch (e) {
				console.warn("Canvas Context Error: " + e.toString());
				return;
			}
			this._onDraw();
		},
		addRibbon: function() {
			var dir = Math.round(random(1, 9)) > 5 ? "right" : "left",
				stop = 1000,
				hide = 200,
				min = 0 - hide,
				max = this._width + hide,
				movex = 0,
				movey = 0,
				startx = dir === "right" ? min : max,
				starty = Math.round(random(0, this._height));
			if (/^(top|min)$/i.test(this._options.verticalPosition)) {
				starty = 0 + hide;
			} else if (/^(middle|center)$/i.test(this._options.verticalPosition)) {
				starty = this._height / 2;
			} else if (/^(bottom|max)$/i.test(this._options.verticalPosition)) {
				starty = this._height - hide;
			}
			var ribbon = [],
				point1 = new Point(startx, starty),
				point2 = new Point(startx, starty),
				point3 = null,
				color = Math.round(random(0, 360)),
				delay = 0;
			while (true) {
				if (stop <= 0) break;
				stop--;
				movex = Math.round((Math.random() * 1 - 0.2) * this._options.horizontalSpeed);
				movey = Math.round((Math.random() * 1 - 0.5) * (this._height * 0.25));
				point3 = new Point();
				point3.copy(point2);
				if (dir === "right") {
					point3.add(movex, movey);
					if (point2.x >= max) break;
				} else if (dir === "left") {
					point3.subtract(movex, movey);
					if (point2.x <= min) break;
				}
				ribbon.push({
					point1: new Point(point1.x, point1.y),
					point2: new Point(point2.x, point2.y),
					point3: point3,
					color: color,
					delay: delay,
					dir: dir,
					alpha: 0,
					phase: 0
				});
				point1.copy(point2);
				point2.copy(point3);
				delay += 4;
				color += this._options.colorCycleSpeed;
			}
			this._ribbons.push(ribbon);
		},
		_drawRibbonSection: function(section) {
			if (section) {
				if (section.phase >= 1 && section.alpha <= 0) {
					return true;
				}
				if (section.delay <= 0) {
					section.phase += 0.02;
					section.alpha = Math.sin(section.phase) * 1;
					section.alpha = section.alpha <= 0 ? 0 : section.alpha;
					section.alpha = section.alpha >= 1 ? 1 : section.alpha;
					if (this._options.animateSections) {
						var mod = Math.sin(1 + section.phase * Math.PI / 2) * 0.1;
						if (section.dir === "right") {
							section.point1.add(mod, 0);
							section.point2.add(mod, 0);
							section.point3.add(mod, 0);
						} else {
							section.point1.subtract(mod, 0);
							section.point2.subtract(mod, 0);
							section.point3.subtract(mod, 0);
						}
						section.point1.add(0, mod);
						section.point2.add(0, mod);
						section.point3.add(0, mod);
					}
				} else {
					section.delay -= 0.5;
				}
				var s = this._options.colorSaturation,
					l = this._options.colorBrightness,
					c = "hsla(" + section.color + ", " + s + ", " + l + ", " + section.alpha + " )";
				this._context.save();
				if (this._options.parallaxAmount !== 0) {
					this._context.translate(0, this._scroll * this._options.parallaxAmount);
				}
				this._context.beginPath();
				this._context.moveTo(section.point1.x, section.point1.y);
				this._context.lineTo(section.point2.x, section.point2.y);
				this._context.lineTo(section.point3.x, section.point3.y);
				this._context.fillStyle = c;
				this._context.fill();
				if (this._options.strokeSize > 0) {
					this._context.lineWidth = this._options.strokeSize;
					this._context.strokeStyle = c;
					this._context.lineCap = "round";
					this._context.stroke();
				}
				this._context.restore();
			}
			return false;
		},
		_onDraw: function() {
			for (var i = 0, t = this._ribbons.length; i < t; ++i) {
				if (!this._ribbons[i]) {
					this._ribbons.splice(i, 1);
				}
			}
			this._context.clearRect(0, 0, this._width, this._height);
			for (var a = 0; a < this._ribbons.length; ++a) {
				var ribbon = this._ribbons[a],
					numSections = ribbon.length,
					numDone = 0;
				for (var b = 0; b < numSections; ++b) {
					if (this._drawRibbonSection(ribbon[b])) {
						numDone++;
					}
				}
				if (numDone >= numSections) {
					this._ribbons[a] = null;
				}
			}
			if (this._ribbons.length < this._options.ribbonCount) {
				this.addRibbon();
			}
			requestAnimationFrame(this._onDraw);
		},
		_onResize: function(e) {
			var screen = screenInfo(e);
			this._width = screen.width;
			this._height = screen.height;
			if (this._canvas) {
				this._canvas.width = this._width;
				this._canvas.height = this._height;
				if (this._context) {
					this._context.globalAlpha = this._options.colorAlpha;
				}
			}
		},
		_onScroll: function(e) {
			var screen = screenInfo(e);
			this._scroll = screen.scrolly;
		}
	};
	return Factory;
});
new Ribbons();
